Anti-Müllerian hormone reduces growth rate without altering follicular survival in isolated caprine preantral follicles cultured in vitro

2017 ◽  
Vol 29 (6) ◽  
pp. 1144 ◽  
Author(s):  
R. M. P. Rocha ◽  
L. F. Lima ◽  
I. R. Brito ◽  
G. M. Silva ◽  
H. H. V. Correia ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cytochrome P450 ◽  
Hormone Receptors ◽  
Mrna Levels ◽  
Follicular Growth ◽  
Steroid Secretion ◽  
Preantral Follicles ◽  
Treatment Groups ◽  
Cytochrome P450 Family

The aim of the present study was to evaluate the effect of anti-Müllerian hormone (AMH), with and without FSH, on the in vitro development of isolated caprine preantral follicles, as well as follicular steroid production and mRNA levels of AMH, hormone receptors (AMH and FSH), CYP19A1 (cytochrome P450, family 19, subfamily A, polypeptide 1), CYP17 (cytochrome P450, family 17, subfamily A, polypeptide 1), HSD3B (3-beta-hydroxysteroid dehydrogenase) and Myc (myelocytomatosis oncogene). Isolated secondary follicles were cultured in minimum essential medium alpha (α-MEM+) alone or supplemented with 50 ng mL–1 AMH and/or 100 ng mL–1 FSH added sequentially on different days of culture. Follicles were cultured for a total of 18 days, with different media during the first (Days 0–9) and second (Days 10–18) halves of the culture period, resulting in six treatment groups, as follows: α-MEM+/α-MEM+, FSH/FSH, AMH/AMH, AMH+FSH/AMH+FSH, AMH/FSH, and FSH/AMH. Follicle development was evaluated on the basis of follicular growth, oocyte maturation and steroid secretion. There was a decrease in follicular growth rate in the AMH, AMH + FSH and AMH/FSH treatment groups compared with α-MEM+ and FSH treatment groups (P < 0.05). However, the different culture conditions had no effect on rates of meiotic resumption and steroid secretion (P > 0.05). Moreover, follicles cultured in the presence of FSH had lower levels of AMH receptor type II (AMHRII) mRNA compared with non-cultured control (freshly isolated follicles), and the AMH and AMH/FSH treatment groups. In conclusion, AMH reduces the follicular growth rate of isolated goat preantral follicles in vitro without affecting follicular survival.

Stability of housekeeping genes and expression of locally produced growth factors and hormone receptors in goat preantral follicles

Zygote ◽  
2010 ◽  
Vol 19 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Isana M. A. Frota ◽  
Cintia C. F. Leitão ◽  
José J. N. Costa ◽  
Ivina R. Brito ◽  
Robert van den Hurk ◽  
...  
Keyword(s):  
Growth Factors ◽  
Hormone Receptors ◽  
Rna Extraction ◽  
Housekeeping Genes ◽  
Stable Gene ◽  
Mrna Levels ◽  
Preantral Follicles ◽  
The Stability ◽  
Suitable Reference

SummaryThe aim of the present study was to investigate the stability of six housekeeping genes, and the relative expression of growth factors (EGF, GDF-9, BMP-15, VEGF, FGF-2, BMP-6, IGF-1 and KL) and hormone receptors (FSH, LH and GH) in goat preantral follicles. To evaluate to stability of housekeeping genes micro-dissected fresh follicles (150–200 μm) as well as follicles that have been in vitro cultured for 12 days were used. In addition, isolated fresh follicles were used to compare expression of various growth factors and hormone receptors before culture. Both fresh and cultured follicles were subjected to total RNA extraction and synthesis of cDNA. After amplification of cDNA by real-time PCR, the geNorm software program was used to evaluate the stability of glyceraldehyde-2-phosphate dehydrogenase (GAPDH), β-tubulin, β-actin, phosphoglycerokinase (PGK), 18S rRNA, ubiquitin (UBQ) and ribosomal protein 19 (RPL-19). In addition, follicular steady-state levels of mRNA from the various growth factors under study were compared. Results demonstrated that, in goat preantral follicles, UBQ and β-actin were the most suitable reference genes and thus could be used as parameters to normalize data from future in vitro studies. In contrast, 18S RNA appeared the least stable gene among the tested housekeeping genes. Analysis of mRNA for several hypophyseal hormone receptors in fresh preantral follicles showed significantly higher FSH-R mRNA levels than those of LH-R and GH-R, and no difference between GH-R and LH-R mRNA levels. In regard growth factor mRNA expression in goat preantral follicles, EGF mRNA levels appeared significantly lower than those of the other studied growth factors. Increasingly higher relative mRNA levels were observed for GDF-9, BMP-15, BMP-6, FGF-2, VEGF, Kl and IGF-1, successively. In conclusion, UBQ and β-actin are the most stable housekeeping genes in fresh and 12-days cultured caprine preantral follicles. Furthermore, in fresh follicles, high levels of FSH-R mRNA are detected while among eight growth factors, IGF-1 is the most highly expressed and EGF the weakest expressed compound.

Activin-A promotes the development of goat isolated secondary follicles in vitro

Zygote ◽  
2013 ◽  
Vol 23 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Cleidson Manoel Gomes da Silva ◽  
Simone Vieira Castro ◽  
Luciana Rocha Faustino ◽  
Giovanna Quintino Rodrigues ◽  
Ivina Rocha Brito ◽  
...  
Keyword(s):  
Growth Rate ◽  
Formation Rate ◽  
Follicular Development ◽  
Activin A ◽  
Mrna Levels ◽  
Follicular Growth ◽  
P450 Aromatase ◽  
Estradiol Levels

SummaryThe role of activin-A in follicular development and on the mRNA expression levels of different genes in goat secondary follicles was evaluated. Goat secondary follicles (≥150 μm) were cultured for 18 days under control conditions or with the addition of either 50 or 100 ng/ml activin-A (Experiment 1). The mRNA levels for the genes that code for activin-A, ActR-IA, ActR-IB, ActR-IIA, ActR-IIB, follicle stimulating hormone receptor (FSH-R) and P450 aromatase were measured in each condition (Experiment 2). We observed that after 6 days of culture, the antrum formation rate was higher in cultures with added activin-A than in the cultured control (P < 0.05). The addition of 50 ng/ml activin-A increased the follicular growth rate in the final third of the culture (days 12–18), resulting in a higher percentage of meiosis resumption (P < 0.05). On day 6, the addition of activin-A (50 ng/ml) increased the levels of ActR-IA mRNA compared with the cultured control (P < 0.05). After 18 days, the addition of 50 ng/ml activin-A significantly increased the levels of its own mRNA compared with the non-cultured control. Moreover, this treatment reduced the mRNA levels of P450 aromatase in comparison with the cultured control (P < 0.05). Higher levels of P450 aromatase mRNA were found for both activin-A treatments compared with the non-cultured control (P < 0.05). No difference in estradiol levels was detected among any of the tested treatments. In conclusion, the addition of activin-A to culture medium stimulated early antrum formation as well as an increase in the daily follicular growth rate and the percentage of meiosis resumption.

scholarly journals The Role of Androgens in Mammals Folliculogenesis

2018 ◽  
Vol 44 (1) ◽  
pp. 15
Author(s):  
Livia Brunetti Apolloni ◽  
Jamily Bezerra Bruno ◽  
Benner Geraldo Alves ◽  
José Ricardo de Figueiredo
Keyword(s):  
Androgen Receptor ◽  
In Vitro Culture ◽  
Steroid Hormones ◽  
Oocyte Maturation ◽  
Follicular Development ◽  
Follicular Growth ◽  
Preantral Follicles ◽  
Ovarian Cells

Introduction: Steroid hormones production is a physiological process termed steroidogenesis. An important stage of this process is the conversion of androgens into estrogens through aromatase enzyme. Furthermore, androgens are important in the process of folliculogenesis, promoting follicular growth in different species. Thus, the aim of this review was to present the process of synthesis, mechanism of action, and importance of androgens in folliculogenesis. Additionally, the main results of in vitro culture of ovarian cells in the presence of these hormones were emphasized.Review: Folliculogenesis begins in prenatal life in most of species and can be defined as the process of formation, follicular growth, and oocyte maturation. Preantral follicles represent 95% of the follicular population and assisted reproductive technologies have been developed (e.g., Manipulation of Oocytes Enclosed in Preantral Follicles - MOEPF) in order to avoid the great follicle loss that occurs naturally in vivo by atresia. The MOEPF aim to obtain a large number of competent oocytes from preantral follicles and then subject to in vitro maturation, fertilization, and culture for embryo production. However, the development of an efficient medium to ensure the follicular survival and oocyte maturation is the major challenge of this biotechnology. To achieve the success on in vitro culture, the effects of substances as androgens on follicular development have been evaluated. Androgens are steroid hormones produced in theca cells (TC) that are fundamental for follicular growth. These cells provide all the androgens required by the developing follicles for conversion into estrogens by the granulosa cells (GC). Androgens receptors (AR) are localized in cell cytoplasm of all follicular categories, being more expressed in preantral follicles. The androgen pathway initiates through its connection to its receptor, making a complex androgen-AR, that in the nucleus helps on the process of gene transcription related with follicular survival. This mechanism is androgen receptor genomic activity. In addition to genomic action, there is an androgen receptor non-genomic activity. This occurs through activation of AR and its interaction with different signaling molecules located on the cell membrane, triggering events that aid in the follicular development. Regardless of the androgens actions, ovarian cells of several species subjected to in vitro culture have shown the importance of these hormones on the follicle development. Recent studies demonstrated that androgens addition on the culture medium stimulated the activation of preantral follicles (bovine and caprine), antrum formation (swine), survival (non-primate), and oocyte maturation (antral follicles; bovine). Also, some studies suggest that the addition of these hormones on in vitro culture is dose-dependent and species-specific.Conclusion: This review shows the role of androgens in different stages of follicular development and its action as a substrate for steroidogenesis and transcription of genes related to follicular survival and oocyte maturation. However, when these hormones should be added during in vitro follicular culture and which concentration is required remains unclear, being necessary more studies to elucidate these aspects.

Culture of goat preantral follicles in situ associated with mesenchymal stem cell from bone marrow

Zygote ◽  
2019 ◽  
Vol 28 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Camila Arrivabene Neves ◽  
Lucilene dos Santos Silva ◽  
Camila Ernanda Sousa de Carvalho ◽  
Marina Silva Carvalho ◽  
José Lindenberg Rocha Sarmento ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Culture Medium ◽  
Reduced Glutathione ◽  
Follicular Growth ◽  
Morphological Classification ◽  
Nitrite Concentration ◽  
Preantral Follicles ◽  
Rate Of Activation

SummaryThis study aims to develop an in vitro co-culture system of in situ goat preantral follicles with bone marrow-derived mesenchymal stem cells (BM-MSC), evaluating the influence of these cells on follicular growth, rate of activation and morphologically normal follicles. Fragments of ovarian cortex were cultured for 1 or 7 days in the presence of BM-MSC (BM-MSC+) and absence of BM-MSC (BM-MSC−). Histological sections of the fragments were analysed and data were obtained regarding morphological classification, survival rate of morphologically normal follicles and rate of follicular activation. Culture medium on days 1 and 7 was also sampled for nitrite concentration and reduced glutathione activity. There was a reduction (P < 0.05) in the percentage of morphologically normal follicles in the BM-MSC+ compared with the fresh control only on the seventh day of culture. When comparing treatments, on the seventh day of culture, a higher rate of morphologically normal preantral follicles was observed in BM-MSC+ (P < 0.05). In both treatments, primordial and developing follicle rates were similar to the fresh control (P > 0.05). When comparing treatments with each other, as well as with the fresh control, no differences were observed in follicular diameter (P > 0.05) or nitrite concentration (P > 0.05). The concentration of reduced glutathione was lower on the seventh day of co-culture in both treatments (P < 0.05). In conclusion, co-culture had no influence on follicular or oocyte development. However, it was critical to maintain the survival of preantral follicles during 7 days of culture.

scholarly journals Orphan Nuclear Receptor NR4A1 Is a Negative Regulator of DHT-Induced Rat Preantral Follicular Growth

2012 ◽  
Vol 26 (12) ◽  
pp. 2004-2015 ◽  
Author(s):  
Kai Xue ◽  
Jia-yin Liu ◽  
Bruce D. Murphy ◽  
Benjamin K. Tsang
Keyword(s):  
Receptor Antagonist ◽  
Nuclear Receptor ◽  
Mrna Abundance ◽  
Orphan Nuclear Receptor ◽  
Follicular Growth ◽  
Preantral Follicle ◽  
Follicle Growth ◽  
Preantral Follicles

Abstract Nuclear receptor subfamily 4 group A member1 (NR4A1), an orphan nuclear receptor, is involved in the transcriptional regulation of thecal cell androgen biosynthesis and paracrine factor insulin-like 3 (INSL3) expression. Androgens are known to play an important regulatory role in ovarian follicle growth. Using a chronically androgenized rat model, a preantral follicle culture model and virus-mediated gene delivery, we examined the role and regulation of NR4A1 in the androgenic control of preantral follicular growth. In the present study, Ki67 staining was increased in preantral follicles on ovarian sections from 5α-dihydrotestosterone (DHT)-treated rats. Preantral follicles from DHT-treated rats cultured for 4 d exhibited increased growth and up-regulation of mRNA abundance of G1/S-specific cyclin-D2 (Ccnd2) and FSH receptor (Fshr). Similarly, DHT (1 μm) increased preantral follicular growth and Ccnd2 and Fshr mRNA abundance in vitro. The NR4A1 expression was high in theca cells and was down-regulated by DHT in vivo and in vitro. Forced expression of NR4A1 augmented preantral follicular growth, androstenedione production, and Insl3 expression in vitro. Inhibiting the action of androgen (with androgen receptor antagonist flutamide) or INSL3 (with INSL3 receptor antagonist INSL3 B-chain) reduced NR4A1-induced preantral follicular growth. Furthermore, NR4A1 overexpression enhanced DHT-induced preantral follicular growth, a response attenuated by inhibiting INSL3. In conclusion, DHT promotes preantral follicular growth and attenuates thecal NR4A1 expression in vivo and in vitro. Our findings are consistent with the notion that NR4A1 serves as an important point of negative feedback to minimize the excessive preantral follicle growth in hyperandrogenism.

Trans-resveratrol modulates the catalytic activity and mRNA expression of the procarcinogen-activating human cytochrome P450 1B1

2000 ◽  
Vol 78 (11) ◽  
pp. 874-881 ◽  
Author(s):  
Thomas KH Chang ◽  
Wendy BK Lee ◽  
Hin Hin Ko
Keyword(s):  
Gene Expression ◽  
Cytochrome P450 ◽  
Catalytic Activity ◽  
Pcr Analysis ◽  
Mrna Levels ◽  
Toxic Response ◽  
Cytochrome P450 1B1 ◽  
Cyp1b1 Mrna ◽  
Mcf 7

The present study was performed to determine if trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) modulates the catalytic activity and gene expression of cytochrome P450 1B1 (CYP1B1). In vitro, trans-resveratrol decreased human recombinant CYP1B1-catalyzed 7-ethoxyresorufin O-dealkylation activity, with an IC50 value of 1.4 ± 0.2 µM (mean ± SEM). Enzyme kinetic analysis indicated that trans-resveratrol inhibited CYP1B1 enzyme activity by a mixed-type inhibition and the apparent Ki was 0.75 ± 0.06 µM. To determine if trans-resveratrol modulates constitutive CYP1B1 gene expression, cultured MCF-7 human breast carcinoma cells were treated with trans-resveratrol. As indicated by RT-PCR analysis, treatment of MCF-7 cells with 10 µM trans-resveratrol decreased relative CYP1B1 mRNA levels after 5 h, but not after 1.5 or 3 h, of exposure. trans-Resveratrol treatment at 5, 7.5, 10, or 20 µM for 5 h produced a concentration-dependent decrease in CYP1B1 mRNA levels. The extent of suppression was ~50% at 20 µM concentration. The suppressive effect was not a consequence of a toxic response to the compound as assessed by a cell proliferation assay. Overall, our novel finding that trans-resveratrol inhibits the catalytic activity and suppresses the constitutive gene expression of CYP1B1 leads to the possibility that this nutraceutical confers protection against toxicity and carcinogenicity induced by compounds that undergo CYP1B1-catalyzed bioactivation.Key words: cytochrome P450, CYP1B1, 7-ethoxyresorufin, nutraceutical, trans-resveratrol.

scholarly journals Insulin and IGF-I are necessary for FSH-induced cytochrome P450 aromatase but not cytochrome P450 side-chain cleavage gene expression in oestrogenic bovine granulosa cells in vitro

2002 ◽  
Vol 174 (3) ◽  
pp. 499-507 ◽  
Author(s):  
JM Silva ◽  
CA Price
Keyword(s):  
Gene Expression ◽  
Cytochrome P450 ◽  
Granulosa Cells ◽  
Side Chain ◽  
Mrna Levels ◽  
Side Chain Cleavage ◽  
P450 Aromatase ◽  
Chain Cleavage ◽  
Igf I

The earliest biochemical indicators of ovarian follicle deviation in cattle include lower oestradiol and free IGF concentrations in subordinate compared with dominant follicles. We determined if decreases in FSH, IGF-I or insulin cause decreased P450 aromatase (P450arom) or P450 cholesterol side-chain cleavage (P450scc) mRNA expression in oestrogenic bovine granulosa cells in vitro. In the first experiment, cells obtained from small follicles (2-5 mm diameter) were cultured in serum-free medium supplemented with physiological concentrations of FSH, IGF-I and insulin for 4 days. A decrease in specific hormone concentration was produced by replacing 70% of spent medium with medium devoid of FSH, insulin, or insulin and IGF-I on day 4 and again on day 5 of culture. Cultures were terminated on day 7. A reduction in FSH concentrations during the last 3 days of culture decreased P450arom and P450scc mRNA levels. A reduction in insulin reduced P450arom but not P450scc mRNA levels, and a reduction of both insulin and IGF-I concentrations further decreased P450arom mRNA levels and decreased P450scc mRNA levels. In a second experiment, cells obtained from small follicles (2-5 mm diameter) were cultured with insulin (100 ng/ml) without FSH for 4 days, and then insulin was withdrawn from the culture and FSH added for a further 3 days. The withdrawal of insulin decreased (P<0.02) oestradiol accumulation and reduced P450arom mRNA to below detectable levels, but did not affect P450scc mRNA levels. The addition of FSH transiently increased oestradiol secretion and P450arom mRNA levels, but P450arom mRNA levels were undetectable at the end of the culture period. The addition of FSH significantly enhanced P450scc mRNA levels and progesterone accumulation. These data demonstrated that a reduction of insulin-like activity reduced aromatase gene expression in bovine follicles without necessarily affecting progesterone synthetic capability, and thus may initiate follicle regression in cattle at the time of follicle divergence.

scholarly journals Characterization of the Stringent Response and relBbu Expression in Borrelia burgdorferi

2003 ◽  
Vol 185 (3) ◽  
pp. 957-965 ◽  
Author(s):  
Julia Bugrysheva ◽  
Elena Y. Dobrikova ◽  
Marina L. Sartakova ◽  
Melissa J. Caimano ◽  
Thomas J. Daniels ◽  
...  
Keyword(s):  
Growth Rate ◽  
16S Rrna ◽  
Borrelia Burgdorferi ◽  
Stringent Response ◽  
Growth Conditions ◽  
Start Codon ◽  
Rrna Synthesis ◽  
Sequencing Analysis ◽  
Mrna Levels

ABSTRACT The stringent response is a global bacterial response to nutritional stress mediated by (p)ppGpp. We previously found that both noninfectious Borrelia burgdorferi strain B31 and infectious B. burgdorferi strain N40 produced large amounts of (p)ppGpp during growth in BSK-H medium and suggested that the stringent response was triggered in B. burgdorferi under these conditions. Here we report that (p)ppGpp levels in B. burgdorferi growing in BSK-II or BSK-H medium are not further increased by nutrient limitation or by serine hydroxamate-induced inhibition of protein synthesis and that the presence of (p)ppGpp during growth of N40 in BSK-H medium is not associated with decreased 16S rRNA synthesis. Decreased 16S rRNA synthesis was associated with the decreased growth rate of N40 seen during coculture with tick cells, which are growth conditions that were previously shown to decrease (p)ppGpp levels. One-half as much of the mRNA of the gene encoding the Rel protein of B. burgdorferi (relBbu ) was produced by B31 as by N40 during in vitro growth (2 ± 0.5 and 4 ± 0.8 fg of relBbu mRNA/ng of total Borrelia RNA, respectively). Although the amounts of N40 relBbu mRNA were identical during growth in vitro and in rat peritoneal chambers, they were markedly decreased during growth in nymphal ticks. In contrast to the lack of change in relBbu mRNA levels, larger amounts of a 78-kDa protein that was cross-reactive with antibodies to Bacillus subtilis RelBsu were detected in immunoblots of N40 lysates after growth in rat peritoneal chambers than after growth in vitro. Differences in the level of production of (p)ppGpp between B31 and N40 could not be explained by differences in relBbu promoters since identical transcriptional start sites 309 nucleotides upstream from the B31 and N40 relBbu ATG start codon and identical σ70-like promoters were identified by primer extension and sequencing analysis. relBbu complemented an Escherichia coli CF1693 relA spoT double mutant for growth on M9 minimal medium, and the transformed cells produced relBbu mRNA. These results indicate that relBbu is functional and that its transcription and translation and production of (p)ppGpp are affected by environmental conditions in strains N40 and B31. They also suggest that in B. burgdorferi, an organism with few rRNA operons that grows slowly, the role of (p)ppGpp may differ from the classic role played by this molecule in E. coli and that (p)ppGpp may not be responsible for growth rate control.

scholarly journals The Roles of the miRNAome and Transcriptome in the Ovine Ovary Reveal Poor Efficiency in Juvenile Superovulation

Animals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 239
Author(s):  
Xiaosheng Zhang ◽  
Chunxiao Dong ◽  
Jing Yang ◽  
Yihai Li ◽  
Jing Feng ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
High Throughput Sequencing ◽  
Hormone Receptors ◽  
Hormone Secretion ◽  
Oocyte Quality ◽  
Differentially Expressed ◽  
Messenger Rnas ◽  
Animal Cloning ◽  
Developmental Capacity ◽  
Cytochrome P450 Family

Juvenile superovulation can provide a wealth of oocyte material for embryo production, animal cloning, and genetic modification research, but embryos derived from juvenile oocytes show poor efficiency in subsequent developmental capacity. In order to reveal the formation mechanism of large numbers of follicles and poor oocyte quality in juvenile ovaries under superovulation treatment, differentially expressed microRNAs (miRNAs) and messenger RNAs (mRNAs) were characterized and investigated in the ovaries of lambs and adult sheep using high-throughput sequencing technology. The majority of differentially expressed miRNAs (337/358) were upregulated in lamb libraries. The expression levels of mRNAs related to hormone receptors (follicle-stimulating hormone receptor, FSHR; luteinizing hormone/choriogonadotropin receptor, LHCGR; estrogen receptor 1, ESR1), steroid hormone secretion (cytochrome P450 family 11 subfamily A member 1, CYP11A1; cytochrome P450 family 17 subfamily A member 1, CYP17A1; cytochrome P450 family 19 subfamily A member 1, CYP19A1), and oocyte quality (pentraxin 3, PTX3; BCL2 apoptosis regulator, BCL2; caspase 3, CASP3) were significantly different between the lamb and adult libraries. The miRNA aor-miR-143, which targets FSHR, was highly and differentially expressed, and PTX3 was predicted to be targeted by oar-miR-485-3p and oar-miR-377-3p in the ovine ovary. A considerable number of miRNAs were predicted to inhibit ESR1 expression in lamb ovaries. In conclusion, oar-miR-143 and FSHR molecules, among others, might regulate follicle formation, and oar-miR-485-3p, oar-miR-377-3p, and PTX3, among others, may be associated with oocyte quality. These identified miRNAs and mRNAs will be beneficial for the prediction of ovarian superovulation potential and screening of oocytes.

Effect of age, retinol, and cholecalciferol on carcass fat and adipocyte number and size in growing lambs

1997 ◽  
Vol 48 (1) ◽  
pp. 7 ◽  
Author(s):  
E. Payne ◽  
S. Watkins
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Adipocyte Differentiation ◽  
Age Effects ◽  
Cell Diameter ◽  
Treatment Groups ◽  
Steady Growth ◽  
Total Fat ◽  
Effect Of Age

To determine whether hyperplasia occurs in young growing meat lambs when fat is laid down we measured the changes in fat parameters with age in Coopworth × Dorset lambs and, in parallel, ran groups treated with retinol and cholecalciferol (reported inhibitors of adipocyte differentiation in vitro), which were slaughtered at 33–34 weeks of age. The lambs were fed a pelleted ration at 30 g/kg body weight from 16 weeks of age and serially slaughtered for age effects in groups of 4, whereas the treatment groups contained 6 lambs. Some lambs developed urethral blockage from pellet feeding so the experiment was terminated early at 33–34 weeks. The lambs showed a steady growth rate and an increase in the proportion of fat in the carcass, total carcass fat, and subcutaneous adipocyte diameter at 25–29 weeks of age. The total number of adipocytes in the carcass derived from diameter measurements on subcutaneous adipocytes and the total carcass fat showed no significant changes. Retinol and cholecalciferol caused significant reductions in cell diameter and increases in total adipocytes but little change in total fat.

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