Epidermal growth factor: a critical factor in fetal maturation?

Area of Science:

• Developmental biology
• Endocrinology
• Fetal programming

Background:

• Epidermal growth factor (EGF) plays a crucial role in cellular growth and differentiation.
• Understanding fetal development and the impact of growth factors is vital for addressing developmental disorders.

Purpose of the Study:

• To investigate the morphological and endocrine effects of exogenous Epidermal Growth Factor (EGF) administration during late-term ovine gestation.
• To assess the impact of EGF on fetal skin, wool follicle development, and organ weights.

Main Methods:

• Infusion of EGF into fetal sheep between 110-125 days of gestation for 3-14 days.
• Monitoring of morphological changes in skin and wool follicles.
• Measurement of organ weights (adrenal, thyroid, liver, kidney, thymus).
• Analysis of hormone levels including cortisol, thyroxine, triiodothyronine (T3), thyrotropin (TSH), prolactin, growth hormone, and placental lactogen.

Main Results:

• Significant skin and wool follicle hypertrophy, with a reduced secondary to primary follicle ratio and fiber degeneration.
• Increased adrenal, thyroid, liver, and kidney weights; decreased thymus weight.
• Adrenal cortical hypertrophy and increased cortisol secretion.
• Thyroid hypertrophy with altered hormone levels (decreased T4, rT3; unchanged T3; increased TSH) despite unchanged TSH receptor affinity.
• Maternal placental lactogen increased with high EGF doses; fetal levels and other hormones remained unchanged.

Conclusions:

• Exogenous EGF administration during late gestation induces substantial morphological and endocrine alterations in fetal sheep.
• EGF significantly impacts skin and wool follicle development and influences adrenal and thyroid function.
• The study provides insights into the role of EGF in fetal development and potential implications for wool production and endocrine regulation.