The mammary gland is a unique organ with the ability to undergo repeated cyclic changes throughout the life of mammals. Among domesticated livestock species, ruminants (cattle and buffalo) constitute a distinct class of livestock species that are known milk producers. Cattle and buffalo contribute to 51 and 13% of the total milk supply in the world, respectively. They also play an essential role in the development of the economy for farming communities by providing milk, meat, and draft power. The development of the ruminant mammary gland is highly dynamic and multiphase in nature. There are six developmental stages: embryonic, prepubertal, pubertal, pregnancy, lactation, and involution. There has been substantial advancement in our understanding of the development of the mammary gland in both mouse and human models. Until now, there has not been a thorough investigation into the molecular processes that underlie the various stages of cow udder development. The current review sheds light on the morphological and molecular changes that occur during various developmental phases in diverse species, with a particular focus on the cow udder. It aims to explain the physiological differences between cattle and non-ruminant mammalian species such as humans, mice, and monkeys. Understanding the developmental biology of the mammary gland in molecular detail, as well as species-specific variations, will facilitate the researchers working in this area in further studies on cellular proliferation, differentiation, apoptosis, organogenesis, and carcinogenesis. Additionally, in-depth knowledge of the mammary gland will promote its use as a model organ for research work and promote enhanced milk yield in livestock animals without affecting their health and welfare.

Background: The mammary gland is a crucial organ in dairy animals, responsible for milk production, regulated by intricate hormonal and cellular interactions. Traditional two-dimensional (2D) cell culture systems used in mammary gland research fail to replicate the complex in vivo environment, limiting the understanding of mammary gland biology. The study explores the advantages of three-dimensional (3D) culture systems for Buffalo Mammary Epithelial Cells (BuMECs), aiming to enhance morphological and functional differentiation compared to 2D cultures. Methods: BuMECs were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM/F12) supplemented with 10% FBS and specific growth factors. For 2D culture, BuMECs were grown on a plastic substratum. For 3D culture, cells were cultured on top of and embedded in growth factor-reduced (GFR) Matrigel. Morphological differentiation was observed under phase-contrast microscopy. Total RNA was extracted and cDNA was synthesized to measure β-casein gene expression using quantitative real-time PCR (qPCR). Protein expression was analyzed by Western blotting, targeting total casein. Result: BuMECs grown in 3D cultures exhibited enhanced morphological differentiation, forming alveolar and ductal structures, unlike the monolayer formation observed in 2D cultures. Rapid formation of duct-like structures was noted within 24 hours in 3D cultures. Functional differentiation was significantly improved, evidenced by a five-fold increase in β-casein mRNA expression and higher protein levels of α, β and κ-casein in 3D cultured cells compared to 2D cultures. Western blot analysis confirmed the elevated casein protein expression in 3D cultures.