An ultrastructural study of spermatogenesis and the morphology of the testis in the nemertean worm Tetrastemma phyllospadicola (Nemertea, Hoplonemertea)

1986 ◽  
Vol 64 (10) ◽  
pp. 2187-2202 ◽  
Author(s):  
Stephen A. Stricker ◽  
Michael J. Cavey
Keyword(s):  
Ultrastructural Study ◽  
Somatic Cells ◽  
Posterior Part ◽  
Spermatogenic Cells

Ripe male specimens of the nemertean worm Tetrastemma phyllospadicola (Nemertea, Hoplonemertea) measure about 7 mm long and characteristically possess 100–200 saccular testes. Each testis connects to a short gonoduct which is lined by myofilament-containing cells. The testicular sac is also lined by cells packed with myofilaments and typically contains scattered clusters of spermatogenic cells and bundles of sperm. During spermatogenesis, a spermatogonium divides mitotically several times and ultimately forms a cluster of primary spermatocytes that remain interconnected by narrow cellular bridges. Spermatocytes undergo meiotic divisions to produce syncytial clones of spermatids. As spermiogenesis proceeds, each spermatid differentiates into a modified spermatozoon with a wavy head measuring about 40 μm long. The head contains a well-developed acrosomal complex situated lateral to the anterior end of the nucleus and a long mitochondrion that lies within a groove in the posterior part of the nucleus. A discrete midpiece is lacking. The centriolar anchoring apparatus comprises nine unbranched spokes, and the tail exhibits a 9 × 2 + 2 arrangement of microtubules. Somatic cells that possess ramifying processes are intimately associated with the spermatogenic clones in each testis. Peculiar attributes of the testes and spermatozoa of this species are discussed with reference to previous accounts of spermatogenesis in nemerteans.

Transcription of the rat and mouse proenkephalin genes is initiated at distinct sites in spermatogenic and somatic cells

1990 ◽  
Vol 10 (7) ◽  
pp. 3717-3726
Author(s):  
D L Kilpatrick ◽  
S A Zinn ◽  
M Fitzgerald ◽  
H Higuchi ◽  
S L Sabol ◽  
...  
Keyword(s):  
Germ Cell ◽  
Somatic Cells ◽  
Tata Box ◽  
Spermatogenic Cell ◽  
Spermatogenic Cells ◽  
Consensus Binding Site ◽  
Base Pairs ◽  
Promoter Motif ◽  
Specific Manner ◽  
Rna Protection

During spermatogenesis, several genes are expressed in a germ cell-specific manner. Previous studies have demonstrated that rat and mouse spermatogenic cells produce a 1,700-nucleotide proenkephalin RNA, while somatic cells that express the proenkephalin gene contain a 1,450-nucleotide transcript. Using cDNA cloning, RNA protection, and primer extension analyses, we showed that transcription of the rat and mouse spermatogenic-cell RNAs is initiated downstream from the proenkephalin somatic promoter in the first somatic intron (intron As). In both species, the germ cell cap site region consists of multiple start sites distributed over a length of approximately 30 base pairs. Within rat and mouse intron As, the region upstream of the germ cell cap sites is GC rich and lacks TATA sequences. A consensus binding site for the transcription factor SP1 was identified in intron As downstream of the proenkephalin germ cell cap site region. These features are characteristic of several previously described promoters that lack TATA sequences. Homologies were also identified between the proenkephalin and rat cytochrome c spermatogenic-cell promoters, including the absence of a TATA box, a multiple start site region, and several common sequences. This promoter motif thus may be shared with other genes expressed in male germ cells.

An ultrastructural study of oogenesis, fertilization, and egg laying in a nemertean ectosymbiont of crabs, Carcinonemertes epialti (Nemertea, Hoplonemertea)

1986 ◽  
Vol 64 (6) ◽  
pp. 1256-1269 ◽  
Author(s):  
Stephen A. Stricker
Keyword(s):  
Ultrastructural Study ◽  
Gravid Female ◽  
Somatic Cells ◽  
Egg Laying ◽  
Egg Mass ◽  
Stages Of Development ◽  
Endocytotic Vesicles ◽  
Brachyuran Crabs ◽  
Germinal Cells ◽  
Sexually Mature

The nemertean worm Carcinonemertes epialti occurs ectosymbiotically on brachyuran crabs and becomes sexually mature while feeding on the eggs of its host. Gravid worms possess numerous saccular ovaries that lie among serially arranged diverticula of the intestine. The epithelium surrounding the lumen of each ovary contains germinal cells at various stages of development and somatic cells. Previtellogenic oocytes are typically situated in the subepidermal region of the ovarian epithelium, whereas vitellogenic oocytes tend to occur toward the intestine. The presence of numerous synthesizing organelles in vitellogenic oocytes indicates that at least some yolk constituents are produced within the ooplasm by an autosynthetic method. A supplemental form of heterosynthetic vitellogenesis may also occur, since somatic cells situated next to yolk-forming oocytes possess putative endocytotic vesicles that might help to transport yolk components derived from ingested crab eggs to the developing oocytes. Fully formed primary oocytes in the lumen of the ovary lack extracellular coats and typically measure 70–75 μm in diameter. Following fertilization, several egg strings that characteristically contain about 200 developing embryos are deposited by each gravid female in the egg mass of the crab.

scholarly journals Transcription of the rat and mouse proenkephalin genes is initiated at distinct sites in spermatogenic and somatic cells.

1990 ◽  
Vol 10 (7) ◽  
pp. 3717-3726 ◽  
Author(s):  
D L Kilpatrick ◽  
S A Zinn ◽  
M Fitzgerald ◽  
H Higuchi ◽  
S L Sabol ◽  
...  
Keyword(s):  
Germ Cell ◽  
Somatic Cells ◽  
Tata Box ◽  
Spermatogenic Cell ◽  
Spermatogenic Cells ◽  
Consensus Binding Site ◽  
Base Pairs ◽  
Promoter Motif ◽  
Specific Manner ◽  
Rna Protection

During spermatogenesis, several genes are expressed in a germ cell-specific manner. Previous studies have demonstrated that rat and mouse spermatogenic cells produce a 1,700-nucleotide proenkephalin RNA, while somatic cells that express the proenkephalin gene contain a 1,450-nucleotide transcript. Using cDNA cloning, RNA protection, and primer extension analyses, we showed that transcription of the rat and mouse spermatogenic-cell RNAs is initiated downstream from the proenkephalin somatic promoter in the first somatic intron (intron As). In both species, the germ cell cap site region consists of multiple start sites distributed over a length of approximately 30 base pairs. Within rat and mouse intron As, the region upstream of the germ cell cap sites is GC rich and lacks TATA sequences. A consensus binding site for the transcription factor SP1 was identified in intron As downstream of the proenkephalin germ cell cap site region. These features are characteristic of several previously described promoters that lack TATA sequences. Homologies were also identified between the proenkephalin and rat cytochrome c spermatogenic-cell promoters, including the absence of a TATA box, a multiple start site region, and several common sequences. This promoter motif thus may be shared with other genes expressed in male germ cells.

scholarly journals IGSF11 is required for pericentric heterochromatin dissociation during meiotic diplotene

PLoS Genetics ◽  
2021 ◽  
Vol 17 (9) ◽  
pp. e1009778
Author(s):  
Bo Chen ◽  
Gengzhen Zhu ◽  
An Yan ◽  
Jing He ◽  
Yang Liu ◽  
...  
Keyword(s):  
Germ Cells ◽  
Sertoli Cells ◽  
Somatic Cells ◽  
Primary Spermatocyte ◽  
Pericentric Heterochromatin ◽  
Spermatogenic Cells ◽  
Testicular Cell ◽  
Reporter System ◽  
Fluorescent Reporter ◽  
Late Pachytene

Meiosis initiation and progression are regulated by both germ cells and gonadal somatic cells. However, little is known about what genes or proteins connecting somatic and germ cells are required for this regulation. Our results show that deficiency for adhesion molecule IGSF11, which is expressed in both Sertoli cells and germ cells, leads to male infertility in mice. Combining a new meiotic fluorescent reporter system with testicular cell transplantation, we demonstrated that IGSF11 is required in both somatic cells and spermatogenic cells for primary spermatocyte development. In the absence of IGSF11, spermatocytes proceed through pachytene, but the pericentric heterochromatin of nonhomologous chromosomes remains inappropriately clustered from late pachytene onward, resulting in undissolved interchromosomal interactions. Hi-C analysis reveals elevated levels of interchromosomal interactions occurring mostly at the chromosome ends. Collectively, our data elucidates that IGSF11 in somatic cells and germ cells is required for pericentric heterochromatin dissociation during diplotene in mouse primary spermatocytes.

Structures related to the germ plasm in mouse

Zygote ◽  
2006 ◽  
Vol 14 (3) ◽  
pp. 231-238 ◽  
Author(s):  
Arkadiy Reunov
Keyword(s):  
Mus Musculus ◽  
Germ Plasm ◽  
Laboratory Mouse ◽  
Posterior Part ◽  
Spermatogenic Cells ◽  
Ultrastructural Alterations ◽  
Late Spermatid ◽  
Embryo Cells ◽  
Chromatoid Bodies

SummaryThis report presents data from ultrastructural and morphometric studies on the germinal-body-like structures, nuage, nuage–mitochondrial clusters and chromatoid bodies in 4.5-day embryo cells and spermatogenic cells of the laboratory mouse Mus musculus. In the 4.5-day embryo cells the germinal-body-like structures that, according to previous data, arise by condensation of mitochondria in Graafian oocytes, were found not to undergo any ultrastructural alterations. In spermatogonia the germinal-body-like structures presumably were transformed into nuage that functioned as ‘intermitochondrial cement’ binding the mitochondrial clusters. In primary spermatocytes mitochondria aggregated by nuage were found with large vacuoles containing membraneous conglomerates that were obviously excreted by organelles into the cytoplasm. The chromatoid bodies that arose in spermatocytes and finally disintegrated in the posterior part of late spermatids seemed not to be implicated in the pathway of the germinal-body-like structure. The dispersion of chromatoid bodies was noted to be accompanied by excretion of membraneous conglomerates by late spermatid mitochondria. The spermatozoa were not found to contain either the germinal-body-like structures or any other germ-plasm-related structures.

scholarly journals Bisphenol A-induced morphological alterations in Sertoli and spermatogenic cells of immature Shiba goatsin vitro: An ultrastructural study

2004 ◽  
Vol 3 (4) ◽  
pp. 205-210 ◽  
Author(s):  
BIBIN BINTANG ANDRIANA ◽  
TAT WEI TAY ◽  
RYUJI HIRAMATSU ◽  
MOHAMMAD ABDUL AWAL ◽  
YOSHIAKIRA KANAI ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Ultrastructural Study ◽  
Spermatogenic Cells ◽  
Morphological Alterations

scholarly journals An Ultrastructural Study on the Effects of Mono(2-ethylhexyl) Phthalate on Mice Testes: Cell Death and Sloughing of Spermatogenic Cells

2007 ◽  
Vol 83 (4) ◽  
pp. 123-130 ◽  
Author(s):  
Tat Wei TAY ◽  
Bibin Bintang ANDRIANA ◽  
Maki ISHII ◽  
Ehn Kyoung CHOI ◽  
Xiao Bo ZHU ◽  
...  
Keyword(s):  
Cell Death ◽  
Ultrastructural Study ◽  
Spermatogenic Cells ◽  
Ethylhexyl Phthalate

scholarly journals 318 ENHANCEMENT OF FERTILIZATION BY DIGITONIN IN ROUND SPERMATID INJECTION

2005 ◽  
Vol 17 (2) ◽  
pp. 309
Author(s):  
S. Kishigami ◽  
E. Mizutani ◽  
S. Wakayama ◽  
T. Wakayama
Keyword(s):  
Polar Body ◽  
Formation Rate ◽  
Somatic Cells ◽  
Reproductive Technologies ◽  
Round Spermatid ◽  
Spermatogenic Cells ◽  
Second Polar Body ◽  
Pronuclear Formation ◽  
Round Spermatid Injection

Reproductive technologies allow us to produce offspring using a variety of cells including sperm, spermatids, spermatocytes, somatic cells, and even parthenogenetic oocytes. In each of these technologies, failure of pronuclear formation after injection often prevents successful artificial reproduction. One of the possible causes is assumed to be that the breakage of the cytoplasmic membrane by simple pipetting is not enough to expose the nuclei to the ooplasm for pronuclear formation. To overcome this problem, we applied digitonin, a mild nonionic detergent, for the purpose of the permeabilization of cellular and nuclear membranes before injection. In this study, round spermatid cells in the mouse were used as a model because of their low pronuclear formation rate after injection. First, to examine the permeabilization of spermatids by digitonin, spermatid cells were incubated in CZB medium including 10 μg/mL of digitonin. Interestingly, the spermatids were lysed within 30 s after transfer but not other spermatogenic cells or somatic cells. Next, we conducted round spermatid injection (ROSI) using PVP including digitonin in a similar manner. Spermatids were picked up by injection pipette from spermatogenic cells suspended in a drop of PVP. These spermatids were transferred into another PVP drop including 1 μg/mL or 10 μg/mL of digitonin and left for 30 s. These digitonin-treated spermatids were then directly injected into previously activated oocytes. Six hours after injection, the fertilized oocytes were examined. Pronuclear formation rates were calculated as a proportion of oocytes with two pronuclei as well as one second polar body to total oocytes with one second polar body (Table 1). After digitonin treatment, fertilization rates significantly increased compared with ROSI without digitonin (Table 1). Further, these fertilized oocytes developed into blastocysts in vitro at comparable or higher rates. To further elucidate the effects of digitonin pretreatment on in vivo development, embryos were transferred into surrogate mothers 24 h after injection for offspring production. Although it is preliminary, we succeeded in the delivery of pups after ROSI with digitonin pretreatment (8 pups out of 14 transferred embryos). Thus, digitonin pretreatment is suggested to improve the success rate of ROSI. Table 1. Fertilization and in vitro development after ROSI with digitonin

Tumor Diagnosis

1982 ◽  
Vol 40 ◽  
pp. 262-265
Author(s):  
Bruce Mackay
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Diagnosis ◽  
Light Microscopy ◽  
Clinical Examination ◽  
Ultrastructural Study ◽  
Diagnostic Procedures ◽  
Specific Diagnosis ◽  
Transmission Electron ◽  
Microscopic Diagnosis

The broadest application of transmission electron microscopy (EM) in diagnostic medicine is the identification of tumors that cannot be classified by routine light microscopy. EM is useful in the evaluation of approximately 10% of human neoplasms, but the extent of its contribution varies considerably. It may provide a specific diagnosis that can not be reached by other means, but in contrast, the information obtained from ultrastructural study of some 10% of tumors does not significantly add to that available from light microscopy. Most cases fall somewhere between these two extremes: EM may correct a light microscopic diagnosis, or serve to narrow a differential diagnosis by excluding some of the possibilities considered by light microscopy. It is particularly important to correlate the EM findings with data from light microscopy, clinical examination, and other diagnostic procedures.

Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study

1967 ◽  
Vol 25 ◽  
pp. 110-111
Author(s):  
W. G. Banfield ◽  
G. Kasnic ◽  
J. H. Blackwell
Keyword(s):  
Electron Microscope ◽  
Infected Cell ◽  
Microscopic Study ◽  
Intestinal Epithelium ◽  
Ultrastructural Study ◽  
Osmium Tetroxide ◽  
Lead Citrate ◽  
Electron Microscopic ◽  
Virus Particles ◽  
Infected Cells

An ultrastructural study of the intestinal epithelium of mice infected with the agent of epizootic diarrhea of infant mice (EDIM virus) was first performed by Adams and Kraft. We have extended their observations and have found developmental forms of the virus and associated structures not reported by them.Three-day-old NLM strain mice were infected with EDIM virus and killed 48 to 168 hours later. Specimens of bowel were fixed in glutaraldehyde, post fixed in osmium tetroxide and embedded in epon. Sections were stained with uranyl magnesium acetate followed by lead citrate and examined in an updated RCA EMU-3F electron microscope.The cells containing virus particles (infected) are at the tips of the villi and occur throughout the intestine from duodenum through colon. All developmental forms of the virus are present from 48 to 168 hours after infection. Figure 1 is of cells without virus particles and figure 2 is of an infected cell. The nucleus and cytoplasm of the infected cells appear clearer than the cells without virus particles.

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