zygotene

Although zygotene spermatocytes showed slight degeneration with prolonged exposure to high doses, maturation arrest was evident by the increased numbers of cells present.

The results of the microscopic examination showed no clear difference between the densities of spermatogonia type A, primary spermatocytes at the pachytene stage, spermatids at the zygotene stage and spermatozoa in the seminiferous tubules of vaccinated (Figure 2Ba) and control lambs (Figure 2Bb) at week 30 after the primary immunization.

At the stages of meiotic prophase I (i.e., leptotene, zygotene and pacyhtene), the sex chromosomes were positively heteropycnotic and large X1 and X2 associated with each other.

The other germinal cells in this stage were primary spermatocytes in the zygotene and pachytene stage, which were clearly observed in the seminiferous epithelium.

During the second stage of prophase in meiosis, zygotene (where the chromosomes closely associate), the mitochondria tightly envelop the nucleus.

Primary spermatocytes, stained with the anti-SCP3 antibody, were selected to evaluate the respective percentages of leptotene, zygotene, pachytene and diplotene stages.

The preleptotene spermatocytes enter prophase I of meiosis, transform into leptotene, zygotene, pachytene and diplotene cells, which then quickly finish meiosis I forming secondary spermatocytes.

Early prophasic Leptotene, Oogonia enter into meiosis, stage (CN) zygotene, giving rise to oocytes.

This latter cell gives rise to the primary spermatocyte, which quickly undergoes its first meiotic division and passes through 4 prophase stages, leptotene, zygotene, pachytene, and diplotene, before undergoing meiotic metaphase.