Weng Kong Sung

Colcemid effects on homologue pairing and crossing over during fetal mouse oogenesis.

Colcemid was administered to gestational day 13 female mice to test effects on homologue pairing, synapsis and recombination of fetal oogenesis. Pairing abnormalities were detected in pachytene oocytes by light and electron microscopy examination of bivalents and synaptonemal complexes. Reduction of total chiasmata per treated diplotene oocyte (22.74) compared to controls (31.07) was found.

A Method for Obtaining Synaptonemal Complexes of Human Pachytene Oocytes

SUMMARYA method is described for obtaining complete, well-spread synaptonemal complexes of human oocytes for light and electron microscopic examination. Preliminary karyotypes from each technique are presented. Examination of a cell from an aborted XXX fetal ovary revealed trivalent pairing of the X chromatids.

The Cycle of the Seminiferous Epithelium of the Turkish Hamster (Mesocricetus brandti)

The Turkish hamster (Mesocricetus brandti) has become a desirable species for experimentation in testicular function, photoperiod, reproductive hormones and hibernation. Basic data on the kinetics of the seminiferous epithelium have not yet been published. In the present study, the cycle of the seminiferous epithelium was divided into eight stages based on the overall cellular associations of 1540 cross sections of tubules. The mean relative frequencies for stages 1 through 8 were 5.9, 3.3, 11.7, 6.7, 7.2, 28.5, 21.6 and 15.1%, respectively. The absolute duration of the cycle of the seminiferous epithelium was determined by administration of 3H‐thymidine, removal of testes at intevals after injection and autoradiography. The mean duration of one cycle was estimated at 8.0 days and the duration of stages 1 through 8 was 0.5, 0.3, 0.9, 0.5, 0.6, 2.3, 1.7 and 1.2 days, respectively. The duration of meiotic prophase was 11.5 days and of spermiogenesis was 13.8 days. The life span of preleptotene cell was estimated at 1.21 days, leptotene, 0.73 days, zygotene, 0.94 days and pachytene, 7.37 days. The total cycle length of spermatogenesis as usually calculated was 32.0 days.

Genetic characteristics of spermatogenesis in the turkish hamster (mesocricetus brandti) subjected to reduced temperature or light

Abstract 1. 1.|A genetic study of Turkish hamster (Mesocricetus brandti) spermatogenesis exposed to reduced temperature and/or light was made of pachytene pairing, crossing-over and disjunction during testicular regression and recrudescence. 2. 2.|Abnormalities were found in all three mechanisms in all experimental groups particularly in cold exposed testes during recrudescence.

Synaptonemal complex karyotype of the pachytene spermatocytes and oocytes of the Turkish hamster (Mesocricetus brandti)

SUMMARYThe complete synaptonemal complex karyotype of the pachytene spermatocytes and oocytes of the Turkish hamster (Mesocricetus brandti) are described. The species has unique polymorphisms of the X and Y. Multiple configurations of the XY bivalent were seen possibly resulting from an autosomal translocation to the sex chromosomes.