In Rhinella arenarum spermiation occurs as a consequence of LH/FSH increase during the amplexus or by a single dose of hCG, among other gonadotropins. The present study employs an in vitro system to study the mechanism of action of hCG in the spermiation of R. arenarum. Testicular fragments were incubated for 2h at 28°C in the presence or absence of 20IU hCG with or without different PKA/PKC in...

Spermiation, the release of late spermatids from the Sertoli cell, is disrupted by a number of toxicants. Control of the spermiation process, and the proteins that interact to adhere mature spermatids to Sertoli cells, is poorly understood. In these studies we used immunohistochemistry, coimmunoprecipitation/Western blotting, and mass spectrometry to refine an earlier model of sperm adhesion pr...

One species of Hemichordata, Balanoglossus misakiensis, is then acorn worm originally reported from the intertidal zone of the Miura Peninsula on the Pacific Ocean side of Japan. We histologically examined the reproductive cycle of the population of this species, which inhabits only the sublittoral zone in the Sea of Japan. Testes and ovaries began to develop at the beginning of May 2003 and we...

The present study reports on the daily and seasonal variations in plasma melatonin concentration, and also in optic tectum and hypothalamus melatonin binding sites, in male European sea bass maintained under natural photoperiod (NP) or continuous light (LL) from early stages of development. Samples were collected on a 24-h cycle, at four physiological phases of their first annual reproductive c...

BACKGROUND In rainbow trout (Oncorhynchus mykiss), the endocrine control of spermiation is not fully understood. Besides 11ketotestosterone (11KT) and 17alpha, 20beta-dihydroxyprogesterone (MIS), the potential physiological ligand of the mineralocorticoid receptor (MR) 11-deoxycorticosterone (DOC), is a credible candidate in O. mykiss spermiation regulation as spermiation is accompanied with ch...

In this study, the benefits of using the first Iranian made GnRHa[D-Ala6 des Gly10] mGnRH ethylamide, to induce spermiation in male rainbow trout, Oncorhynchus mykiss, were evaluated, In addition, its effect on acceleration and synchronization, quality and quantity of milt and the plasma Testosterone (T) fluctuations were examined. For these purposes, 40 non-spermiating male rainbow trouts were...

This paper briefly describes recent data we have obtained on gonadotropin (GtH) regulation of the testicular somatic cells in relation to spermatogenesis and sperm production (spermiation). Throughout the spermatogenetic cycle, the number of testicular GtH binding sites was maximum before and during spermiation. While testicular sensitivity to s-GtH for 11 -ketotestosterone (11 1 KT) secretion ...

This commentary is to critique the revised World Health Organization (WHO) semen analysis manual as it pertains to characteristics of a spermatozoon at spermiation. The aims of the revised WHO manual include improving the 'quality of semen analysis' without any restriction to clinical use. Furthermore, the manual states that semen analysis may be useful for (a) 'investigating male fertility sta...

BACKGROUND Luteinizing hormone-releasing hormone (LHRH) is an exogenous hormone commonly used to induce spermiation in anuran amphibians. Over the past few decades, the LHRH dose administered to individuals and the frequency of injection has been highly variable. The sperm-release responses reported have been correspondingly diverse, highlighting a need to quantify dose-response relationships o...