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Updated: Feb 26, 2026
Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland
Published on: December 1, 2015
Temporal and spatial heterogeneity in milk and immune-related gene expression during mammary gland involution in
K Singh1, C V C Phyn2, M Reinsch1
1AgResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton 3214, New Zealand.
Insights
Mammary gland involution in dairy cows shows significant heterogeneity in gene expression and tissue morphology. Understanding these variations is key to improving milk production.
Area of Science:
- Dairy cattle reproduction and physiology
- Molecular biology and gene expression
- Mammary gland biology and involution
Background:
- Mammary gland involution is a complex process involving significant tissue remodeling and changes in gene expression.
- Heterogeneity in involution processes can impact overall milk production and udder health in dairy cows.
Purpose of the Study:
- To investigate heterogeneity in tissue morphology, milk protein, and immune-related gene expression during lactation and involution in dairy cow mammary glands.
- To analyze apoptosis of epithelial cells and identify variations across different mammary gland regions and time points postmilking.
Main Methods:
- Postmortem collection of mammary tissue from different regions (alveolar, cisternal, peripheral) at various time points postmilking (0-72 h).
- Analysis of CSN1NS1, LALBA, lactoferrin (LF), and mammary serum amyloid A3 (M-SAA3) mRNA expression using quantitative methods.
- Histological analysis, in situ hybridization, and assessment of phosphorylated STAT5 and STAT3 proteins and apoptosis.
Main Results:
- Milk protein gene expression (CSN1NS1, LALBA) decreased, while immune-related genes (LF, M-SAA3) increased during involution.
- Significant variability in gene expression was observed between cows and mammary gland regions, particularly in alveolar tissue.
- Alveoli demonstrated asynchronous entry into involution, with increasing LF expression and pronounced heterogeneity over time.
Conclusions:
- Mammary gland involution is characterized by asynchronous alveolar involution and significant inter-cow variability in tissue morphology and gene expression.
- Understanding the mechanisms initiating involution offers potential for enhancing dairy cow milk production.
- Regional differences in gene expression and involution rates highlight the complexity of mammary gland remodeling.
Abstract:
The aim of this study was to investigate heterogeneity in tissue morphology, milk protein and immune-related gene expression, and apoptosis of epithelial cells in the lactating and involuting mammary glands of the dairy cow. Mammary tissue from different regions of the gland (alveolar, cisternal, and peripheral) was collected postmortem from nonpregnant, pasture-fed, Holstein-Friesian primiparous cows in mid-lactation that were killed at different time points postmilking: 0, 6, 12, 18, 24, 36, and 72 h (n = 6 per time point). The CSN1NS1 and LALBA mRNA was decreased in alveolar, cisternal, and peripheral tissue by 12 to 36 h postmilking. In contrast, lactoferrin (LF) and mammary serum amyloid A3 (M-SAA3) mRNA was increased in these regions by 36 to 72 h. During lactation, more variability was present in gene expression in alveolar tissue between cows and between quarters within a cow, than within quarters. Histological analysis indicated the alveolar tissue from lactating cows was mostly uniform in structure; however, in situ hybridization indicated that although most of the alveolar tissue expressed milk proteins, the level of expression varied within and between alveoli. This heterogeneity became more pronounced with involution and with increasing regions of alveoli expressing lactoferrin, indicating that alveoli enter involution asynchronously. The peripheral and cisternal tissue had more variability in gene expression between cows compared with the alveolar tissue. The M-SAA3 signal was more intense in the cisternal tissue and less intense than the peripheral compartment compared with LF particularly in the earlier time points. In addition, between cows within the later time points, differences were observed in tissue morphology, the levels of milk protein and immune-related gene expression, and phosphorylated signal transducer and activator of transcription (STAT) 5-P and STAT3-P proteins, and degree of apoptosis, indicating that involution of the mammary gland occurs at different rates between cows. Understanding the mechanisms initiating the process of involution of the mammary gland provides an opportunity for enhancing milk production of the dairy cow.
