Histomorphological evaluation of the digital coronary region at different fetal development stages of Holstein cattle

The scientific literature lacks detailed morphological descriptions of the histological development and cell differentiation of fetal bovine hoof. In this study, 40 extremity members of Holstein bovine fetuses were collected and divided into four groups (G1 to G4) based on the estimated age. Fragments were removed from wall and sole, processed and stained with hematoxylin - eosin (HE) for light microscopy observation. In G1, it was found that the epidermis was very thin, including keratinocyte layers and clusters of mesenchymal cells. In group G2 it was observed that the thickness of the epidermis covering the limbs remained variable and laminar corium developed in the germinal layer. In group G3 it was noted that in the germinal epithelium there were papillae in little advanced development and cells of the stratum corneum in the initial process of keratinization. In G4, the epidermis was well developed with layers distributed homogeneously, containing symmetrical and long papillae and intense production of keratin. In this work, the most important cellular events for the formation of the fetal hoof in Holstein cattle were first described in different stages of their formation.