摘要:

AbstractIn adult mice, neonatal injections of estrogen induce persistent, estrogen‐independent cornification of the vaginal epithelium. Since the occurrence of nodules composed of affected epithelial cells (B cells) is a prodromic phenomenon of the irreversible vaginal alterations, the relationship between the occurrence of B‐cell nodules and the time of DNA synthesis in the vaginal epithelial cells was examined by means of the techniques of serial mapping and autoradiography. B‐cell nodules appeared in the epithelium of mullerian vagina 3–5 days after the initiation of neonatal estrogen treatment, without spatial continuity to cuboidal epithelial cells of the sinus vagina. The time of DNA synthesis was different in B cells from that in both columnar mullerian and cuboidal sinus cells, suggesting that the mother cells of

ISSN:0022-104X    

DOI:10.1002/jez.1402250112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractMale sterility is one of three phenotypic effects of mutations at three loci in region 9F4 to 10C2 of the polyteneXchromosome ofDrosophila melanogaster, female sterility and reduced viability being other mutant effects. The male sterile(ms)alleles at these loci are allelic with lethal mutations. Male sterile mutations are induced at lower frequencies than lethal mutations at these loci by EMS. Because gene products of two of the loci are essential to larval development and the product of the other locus is essential to pupal development, the occurrence ofmsmutations is not restricted to loci whose products function solely in developing adult tissue. Mutations at a locus in 10A2‐5 cause male sterility without adversely influencing viability or female fertility. We conclude that many loci whose products function in nonreproductive tissue can mutate to a form for which male sterility is a secondary effect. Another group of loci encode products that function exclusively in reproductive tissu

ISSN:0022-104X    

DOI:10.1002/jez.1402250113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractCI 628 citrate, an estrogen antagonist, was given as a single intraluminal injection (5 μg) on day 3 to ovariectomized, progesterone‐treated hamsters. This significantly reduced embryo cleavage rate, transformation of morula into blastocyst, and completely inhibited implantation. The effects of the drug could be reversed by estradiol‐17B (1 μg) but not estradiol‐17α (1 μg) injected intraluminally with CI 628 citrate. Our finding suggests a role of estrogen present in hamster preimplantation embryo in the triggering of embryonic differentiation and implantation of the b

ISSN:0022-104X    

DOI:10.1002/jez.1402250114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractGene expression during murine spermatogenesis has been studied using highly enriched populations of cells obtained by velocity sedimentation at unit gravity and further purified by density gradient centrifugation through Percoll. Polypeptides whose synthesis was directed by total cytoplasmic RNA from round spermatids, pachytene spermatocytes, primitive type A spermatogonia, and Sertoli cells in cell‐free translation systems have been compared by two‐dimensional polyacrylamide gel electrophoresis, followed by fluorography. At the level of detection provided by the electrophoretic methods used, each population of cells contained mRNAs encoding over 200 polypeptides, many of wich were present in high abundance in all four cell types. However, for each cell type examined, a minimum of 5–10% of these polypeptides appear to be either specific to or greatly enriched within a particular cell type. Analysis of the polysomal and nonpolysomal cell fractions from pachytene spermatocytes and round spermatids revealed that the two compartments share many identical mRNAs but specific mRNAs are selectively compartmentalized between the cell fractions and between the two cell types. Movement between compartments was seen; e.g., some polypeptides encoded by mRNA found primarily in the nonpolysomal fraction of pachytene cells were later seen in the polysomal fraction from round spermatids. Virtually every other combination was also observed. These results suggest that the control of gene expression at the level of selective production of mRNA and selective utilization of mRNA are among the mechanisms involved in regulation of spermatogenic cell differenti

ISSN:0022-104X    

DOI:10.1002/jez.1402250115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractOvary weight and fat body weight relative to total body weight were ascertained from samples ofRana magnaocularisandRana forreritaken routinely from sympatric populations of the two species. Relative fat body weight reaches a maximum inR. forreriin October and November, about 2 months later than inR. magnaocularis(August and September). Relative ovary weight inR. forrerireaches a maximum in July and August, some 8 to 9 months after the fat body peak. InR. magnaocularis, in contrast, maximum relative ovary weight occurs in November, December, and January, only about 2 to 4 months later than the fat body peak. Both species may capitalize on abundant food in late summer to increase fat storage. Maturation of the ova and the laying of eggs are almost completely asynchronous for the two species, however. These differences are considered from the standpoint that they may represent an example of reproductive character displacement via temporal competitive exclusion.

ISSN:0022-104X    

DOI:10.1002/jez.1402250116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractVideotape recordings were made of hamster follicles ovulating in vitro. These recordings were analyzed to characterize the morphological changes occurring in ovulating follicles and to time various events in the ovulation sequence. Before rupture, the shape of the follicle is transformed from a low to tall profile as shown previously (Martin and Talbot, '81). The complete transition from a low to tall profile required about 22.5 min. During the profile transition, the smooth muscle cells (SMC) in the base of the follicle contract (Martin and Talbot, '81), and the following events were observed. The base of the follicle moved apically. This pressed the cumulus and oocyte against the apical follicle wall, which appeared granular rather than smooth. The size of the antrum decreased presumably due to obliteration of the basal part of the antrum and movement of follicular fluid through the developing rupture site in the apex. The pressing of the cumulus against the apical wall appeared to cause final thinning and opening of the rupture site. The cumulus was extruded in two phases. Phase 1 was rapid (10–60 sec) and resulted in evacuation of about 25% of the cumulus and usually the oocyte from the antrum. Phase 2 required 2–10 min for completion and was accompanied by collapse of the follicle wall. After collapse, the cumulus remained with its follicle and could not be removed by pulling with Watchmaker's forceps. These observations provide new information on the role of SMC in hamster ovulation and characterize extrusion of the cumulus as a two‐phase

ISSN:0022-104X    

DOI:10.1002/jez.1402250117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractIn two asexual planarian strains (Dugesia gonocephalaandDugesia tigrina), reproduction by transverse fission and regeneration is observed under normal conditions and upon decapitation and reserpine treatment. The pattern of asexual reproduction processes in planarians, as it results from our quantitative observations compared with the literature data, indicates that autotomy and regeneration processes have an extremely wide range of possible expressions. In such a heterogeneous situation it is still possible to suppose the existence of a negative cephalic control of fissiparity, similar to the ones involved in general tissue organization and in the regeneration of planarians.

ISSN:0022-104X    

DOI:10.1002/jez.1402250118

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA complete reversal of seasonally dependent events, like antler growth and change of pelage was achieved in white‐tailed bucks by oral application of melatonin. The drug was administered in a way that simulated the shortening of the natural photoperiod. Mineralization of antlers, shedding of velvet, complete change of summer pelage, and the onset of the rutting behavior was initiated aproximately 2 months ahead of tim

ISSN:0022-104X    

DOI:10.1002/jez.1402250119

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractUncapacitated boar sperm treated with the divalent cation ionophore A23187 in the presence of calcium bind to and penetrate zone‐free hamster eggs. Penetration by ionophore‐treated sperm is, however, blocked when sperm are pretreated with antisperm plasma membrane Fab. The antibody apparently interferes with the interaction of sperm surface antigens with the egg plasma membrane since the antibodies have no significant effect on the motility of sperm nor on the induction of the acrosome reaction by the ionophore. The assay described herein is useful for studying the role of sperm surface antigens in the penetration and fertilization of e

ISSN:0022-104X    

DOI:10.1002/jez.1402250120

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe freshwater shrimpMacrobrachium rosenbergii(de Man) has reflecting superposition compound eyes. Upon adaptation from dark to light conditions, the eye converts from superposition to apposition optics by screening pigment migration. The clear zone, typical of dark‐adapted superposition eyes, persisted after adaptation to 500 lux, when the eye optically behaved like an apposition eye. In this state, optical isolation is maintained by a proximal refractive‐index gradient in the crystalline cone, which only requires the proximal pigment to be in the light‐adapted position around the junction between the cone and rhabdom. Thus, the distal pigment need not invade the clear zone for the eye to convert to apposition optics. This mechanism probably decreases the time required for light adaptation. Furthermore, as a result of total internal reflections in the cone tip, the proximal gradient increases the acceptance

ISSN:0022-104X    

DOI:10.1002/jez.1402250121

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY