Functional and Morphological Characteristics of Goat Rumen Lamina Propria Stromal Cells During Pre-Weaning Development

We examined ruminal lamina propria stromal cells of 5-, 30-, and 60-day-old Boer goats using transmission electron microscopy and immunofluorescence to explore their functional morphology in pre-weaning lambs. At 5 days, cells were poorly differentiated, irregular, organelle-poor, and linked by short processes. By 60 days, fibroblasts, myofibroblasts, macrophages, and lymphocytes were observed, and junctional plaques and vesicles had emerged. Telocytes (TCs) with long, slender processes rich in rough endoplasmic reticulum and mitochondria were observed to release vesicles at 60 days. Immunofluorescence showed that processes of CD34+ vimentin+ cells lengthened with age, forming a dense network at 60 days. α-SMA+ cells were distributed continuously but did not co-localize with CD34+ cells. S100A4+ cells were scarce at 5 days and increased at 30 days. CD34+ S100A4+ cells accumulated at papilla bases, whereas CD34+ vimentin+ cells concentrated at both papilla tips and bases, implying a ruminal epithelial stem cell niche. The results reveal stromal remodeling during pre-weaning rumen development and provide morphological support for the role of stromal cells in regulating epithelial proliferation and differentiation.