Reproduction & Development

Dissection of the Pregnant Cow Reproductive Tract

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The instructor will dissect an early to mid-pregnant bovine reproductive tract.  Data on crown rump length and fetal mass can be collected for use with CIBT’s Fetal Development lab.  Some appreciation of the form and function of the various organs should be developed by students.  This exercise will also serve as a comparative reproduction lab and highlight some of the differences between human and bovine anatomy.

Fetal Development

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Students will measure pictures of developing cow embryos to generate data for size.  Then they will interpret data from graphs to determine age as well as mass.  Students will then compare changes of mass during fetal development with changes in size.  Finally, students will contrast developmental trends in cows with that of humans.  If the dissection of the pregnant bovine uterus was done, the fetal measurements from that lab may also be included.

The Hormones of the Menstrual Cycle

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This laboratory is designed to provide students with the concrete experience of seeing a bovine ovary in different phases of the menstrual cycle.  In the second part of the activity they will graph hormone levels so they can determine which hormone peaks at which part of the menstrual cycle.

Students will examine and dissect cow ovaries to compare a follicle with a corpus luteum.  In addition, they will graph the level of the four main hormones involved in the menstrual cycle and determine when each hormone peaks.

Male Reproductive Physiology

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Students will observe the numbers and motility of sperm by examining wet mounts of bull semen.  Students will develop an understanding of the process of spermatogenesis by gross dissection and microscopic examination of the testes.  An optional demonstration of the bovine male reproductive tract is described that will show students the organization of male reproductive structures and how this contributes to some common medical problems and contraceptive methods in the male.  This lab is divided into several modular components that can be included or removed to accommodate students of different levels and the time available.

Vertebrate Development:  The Japanese Medaka

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Students will observe eggs collected from a freshwater killifish, the Japanese Medaka (Oryzias latipes), from freshly fertilized eggs to hatchling stage and beyond.  When done in conjunction with other laboratory activities, they will determine basic trends in vertebrate development and be able to compare these trends to invertebrate development.