Quantitative Studies of Chicken Somatotrophs during Growth and Development by Morphometry, Immunocytochemistry, and Flow Cytometry

Avian somatotrophs: differentiation, morphology, distribution, and regulation

“…A later peak (15 weeks) in somatotroph number and staining intensity has been observed in a different study employing Leghorns (Tai and Chadwick 1977). Malamed et al (1997) also noted a corresponding increase in somatotroph volume between 5 and 26 weeks in White Leghorns. However, the volume of individual somatotrophs falls between 11 and 18 weeks; thus, the increase in total somatotroph volume is less than the increase in somatotroph number (Malamed et al 1997).…”

“…Malamed et al (1997) also noted a corresponding increase in somatotroph volume between 5 and 26 weeks in White Leghorns. However, the volume of individual somatotrophs falls between 11 and 18 weeks; thus, the increase in total somatotroph volume is less than the increase in somatotroph number (Malamed et al 1997). This increase in volume likely accounts for the increase in pituitary GH content between 5 and 12 weeks and the subsequent plateau (Vasilatos-Younken 1988; Scanes et al 1992;McCann-Levorse et al 1993).…”

“…Similar oscillations in somatotroph number also occur in chickens, with changes occurring earlier in broilers (Hubbard) than in egg-laying (Leghorn) chickens. For instance, somatotroph number (per anterior pituitary gland) begins to increase at 2 weeks in broilers and 5 weeks in Leghorns, reaching adult levels at 6 weeks and 11 weeks, respectively (VasilatosYounken 1988; Malamed et al 1997). A later peak (15 weeks) in somatotroph number and staining intensity has been observed in a different study employing Leghorns (Tai and Chadwick 1977).…”

“…The two lobes were, however, equally potent in hypophysectomized chickens (Brasch and Betz 1971). More recent immunocytochemical and histological studies have concluded that somatotrophs are restricted to the caudal lobe in chickens (Malamed et al 1997) (Fig. 1), doves (Reichardt 1993), pigeons (Hansen and Hansen 1977), Chinese quail (Harrisson 1978), Japanese quail (Mikami et al 1975), white crowned sparrows (Matsuo et al 1969), Peking or Barbary ducks (Marchand et al 1976), and Indian wild birds (Mohanty et al 1997).…”

“…The GH immunoreactivity of individual somatotrophs appears to be distributed normally (Fig. 3), although somatotroph size does not differ along the cephalocaudal axis (Malamed et al 1997). The size of the secretory granules has been determined to be 250-300 nm (Mikami et al 1975) or 100-150 nm (Wada 1975) in the Japanese quail, 200-300 nm in the pigeon (Hansen and Hansen 1977), or 130-220 nm in the Chinese quail (Harrisson 1978).…”