Stereological evaluation of Sertoli cell ontogeny during fetal and neonatal life in two diverse breeds of swine

Abstract

Chinese Meishan (MS) boars have smaller testes due to fewer Sertoli cells compared with White Composite (WC) boars. The objective was to describe Sertoli cell development relative to circulating FSH concentrations in fetal and neonatal MS and WC boars. Testes and blood samples were collected on days 60, 75, 90 and 105 postcoitum (dpc) and 1, 7, 14 and 25 postpartum (dpp). One testis was immunostained for GATA4 or Ki67 antigen to evaluate total and proliferating Sertoli cell numbers respectively. Testicular size was greater (P,0·01) in WC than MS boars at all ages, associated with a greater mass of interstitial tissue. Tubular mass (P,0·01) was greater in prenatal WC boars, but postnatally increased more rapidly (P,0·001) in MS boars, exceeding WC boars by 25 dpp. Sertoli cell numbers increased with age, was greater (P,0·001) in WC than MS boars during prenatal development but increased rapidly (P,0·01) by 1 dpp in MS and thereafter was similar in both breeds. The proportion of Ki67-positive Sertoli cells was maximal at 90 dpc, declining thereafter, did not differ between breeds through 7 dpp, but was greater (P,0·05) in WC than MS boars at 14 and 25 dpp. Plasma FSH concentrations were greater (P,0·05) in WC than MS boars at 75 dpc. FSH concentrations were elevated at 105 dpc (MS) and 1 dpp (WC) but declined thereafter with advancing postnatal age in both breeds. This study illustrates that late gestation represents the period of maximal Sertoli cell proliferation. Despite asynchronous Sertoli cell population growth between breeds during early postnatal life, differential mature Sertoli cell numbers and testicular size are probably due to differences in duration of the proliferative period after 25 dpp, potentially regulated by Sertoli cell maturation and blood-testis barrier formation. These events were not associated with fetal or early postnatal changes in FSH secretion.

Changes of testicular aromatase expression during fetal development in male pigs (sus scrofa)

“…The increase of estrogens specifically at weeks 13 and 15 is also paralleled by a corresponding increase of aromatase mRNA expression, whereas the changes of estrogen concentrations and aromatase activity do not reveal an obvious relationship to FSH. Similarly, low FSH concentrations during that period had also been reported by others (Mc Coard et al 2003). The high concentrations of estrogens in umbilical artery plasma during the last trimester are paralleled by a similar course of estrogen concentrations in amniotic fluid (Robertson et al 1985) and in the urine of sows along pregnancy (Velle 1958).…”

Consequences of a low litter birth weight phenotype for postnatal lean growth performance and neonatal testicular morphology in the pig

“…It has been demonstrated that Sertoli cells provide the environment that protects and nourishes germ cells and supports their development to viable sperm (França and Chiarini-Garcia, 2005) and Sertoli cell proliferation in pigs begins during the prenatal period (McCoard et al, 2002) and continues after birth (Swanlund et al, 1995;França et al, 2000). A critical period of Sertoli cell proliferation occurs during the first 3 weeks after birth (McCoard et al, 2003) and the total number of Sertoli cells achieved will determine testicle size in adulthood, as well as the sperm production capacity (Cooke et al, 1992;Hess et al, 1993). More recently, Flowers (2008) has reported beneficial effects on sperm production for prospective artificial insemination (AI) boars with improved pre-weaning growth, which was achieved by rearing these boars in smaller litters during lactation.…”

Effects of birth weight and standardized litter size on growth performance of boars and subsequent reproductive performance

“…The main determinants of sperm production are Sertoli cells (Sharpe et al, 2003). The most active proliferation of Sertoli cell in pigs begins during the prenatal period and continues for about 30 days postnatal, which ultimately determines the potential for sperm production as an adult (França et al, 2000;McCoard et al, 2002;McCoard et al, 2003). Consequently, it is possible that a boar's potential for sperm production as an adult could be established by the time that it is weaned.…”

“…However, Almeida et al (2013) and Smit et al (2013) observed that one-week-old male piglets with low birth weight had lower testes weight and number of Sertoli cells per testis than their heavier counterparts at birth. This suggests that low birth weight may reduce potential for sperm production in adult boars, because the number of Sertoli cells established before puberty determines sperm production as an adult (McCoard et al, 2003). The positive relationship between sperm production in adult boars and their birth weight was confirmed by Estienne & Harper (2010) and Dysart (2014).…”