scholarly journals Embryonic Diapause: Advances in Understanding the Enigma of Seasonal Delayed Implantation

2012 ◽  
Vol 47 ◽  
pp. 121-124 ◽  
Author(s):  
BD Murphy
Keyword(s):  
Embryonic Diapause ◽  
Delayed Implantation

Coincidence of embryonic growth and uterine protein in the ferret

Development ◽  
1970 ◽  
Vol 24 (2) ◽  
pp. 305-312
Author(s):  
Joseph C. Daniel
Keyword(s):  
Protein Content ◽  
Mitotic Activity ◽  
Circumstantial Evidence ◽  
High Rate ◽  
Embryonic Diapause ◽  
Embryonic Growth ◽  
Delayed Implantation ◽  
Limited Protein ◽  
Implantation Period ◽  
In Cells

The protein content of fluids isolated from the lumen of the uterus of the ferret was correlated with growth of the pre-implantation embryo. Similar observations were made with mink for comparative purposes. Tt is concluded that in the ferret: Protein content rises coincidentally with blastocyst expansion, becoming especially high when the embryo is implanting. The proteins present early in the period are of types that diffuse easily in electrophoresis; they become more like those of serum near the time of implantation. There is no evidence of an embryonic diapause. Mitotic activity in cells of the blastocyst is maintained at a high rate (about 5 %). The prolonged pre-implantation period results from a relatively long mitotic duration in blastocyst cells (80+ min). The protein content found during the pre-blastocyst period is similar to that of mink uterine fluids collected during the period of embryonic diapause. This observation provides additional circumstantial evidence that the embryonic diapause accompanying delayed implantation is related to limited protein availability.

scholarly journals The formation of a hatching line in the serosal cuticle confers multifaceted adaptive functions on the eggshell of a cicada

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Minoru Moriyama ◽  
Kouji Yasuyama ◽  
Hideharu Numata
Keyword(s):  
Protective Role ◽  
Terminal Phase ◽  
Embryonic Diapause ◽  
Insect Eggs ◽  
Ridge Structure ◽  
Conflicting Demands ◽  
Partial Degradation ◽  
Egg Period ◽  
Eggshell Structure

AbstractInsect eggshells must meet various demands of developing embryos. These demands sometimes conflict with each other; therefore, there are tradeoffs between eggshell properties, such as robustness and permeability. To meet these conflicting demands, particular eggshell structures have evolved in diverse insect species. Here, we report a rare eggshell structure found in the eggshell of a cicada, Cryptotympana facialis. This species has a prolonged egg period with embryonic diapause and a trait of humidity-inducible hatching, which would impose severe demands on the eggshell. We found that in eggs of this species, unlike many other insect eggs, a dedicated cleavage site, known as a hatching line, was formed not in the chorion but in the serosal cuticle. The hatching line was composed of a fine furrow accompanied by ridges on both sides. This furrow-ridge structure formed in the terminal phase of embryogenesis through the partial degradation of an initially thick and nearly flat cuticle layer. We showed that the permeability of the eggshell was low in the diapause stage, when the cuticle was thick, and increased with degradation of the serosal cuticle. We also demonstrated that the force required to cleave the eggshell was reduced after the formation of the hatching line. These results suggest that the establishment of the hatching line on the serosal cuticle enables flexible modification of eggshell properties during embryogenesis, and we predict that it is an adaptation to maximize the protective role of the shell during the long egg period while reducing the barrier to emerging nymphs at the time of hatching.

I.—On the Pregnancy Rate in the Lactating Mouse and the Effect of Suckling on the Duration of Pregnancy

1932 ◽  
Vol 51 ◽  
pp. 1-7 ◽  
Author(s):  
L. Mirskaia ◽  
F. A. E. Crew
Keyword(s):  
Mammary Gland ◽  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Inhibitory Action ◽  
Reproductive Activity ◽  
Delayed Implantation ◽  
Prolonged Pregnancy ◽  
Suggested Explanation ◽  
Duration Of Pregnancy

Summary1. The pregnancy rate of primiparæ, suckling their young, was, in this experiment, 24·1 per cent.; that of multiparæ suckling their young, 50 per cent. It is shown that this difference is not due to differences in the incidence of ovulation associated with postpartum œstrus. The suggested explanation of this difference between puberal and adult groups is that a certain level of somatic maturity is a prerequisite for full reproductive activity.2. In all cases the duration of pregnancy was prolonged. The degree of prolongation was variable and could not be related to the number of young in the uterus or suckling. The results provide no support for the suggestion that this prolongation, due to delayed implantation of the fertilised ova, is to be referred to an inhibitory action on the part of the mammary gland. The suggestion is made that the delayed implantation and prolonged pregnancy are due to inability on the part of the corpus luteum to cater adequately for implantation and lactation synchronously.

scholarly journals Involvement of the vomeronasal organ and prolactin in pheromonal induction of delayed implantation in mice

Reproduction ◽  
1980 ◽  
Vol 59 (1) ◽  
pp. 223-228 ◽  
Author(s):  
J. F. Bellringer ◽  
H. P. M. Pratt ◽  
E. B. Keverne
Keyword(s):  
Vomeronasal Organ ◽  
Delayed Implantation
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