PubMed · 10150243
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M S Myerson, J H Bowker, J W Brodsky, S Trevino. 1994. Symposium: partial foot amputations.. https://pubmed.ncbi.nlm.nih.gov/10150243/
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The number of olfactory projection neurons (OPNs) in the brain of the juvenile and adult shore crab Carcinus maenas continues to increase during the life of the animal. In vivo labeling of adult crabs with the proliferation marker bromodeoxyuridine (BrdU) revealed a group of proliferating neuronal precursor cells in the lateral soma clusters (LCs) and in the soma clusters of the hemiellipsoid bodies (HBCs). The LCs contain the cell bodies of the olfactory projection neurons and the HBCs house the cell bodies to which the OPNs project. The aim of the present study was to examine whether the input from primary olfactory afferents has any influence on the rate of proliferation and survival of the neuronal precursors in the central olfactory pathways of C. maenas. Different sets of experiments involving BrdU injection and its immunocytochemical detection combined with unilateral amputation of the antennule that houses the olfactory organ were carried out. Our results show that the missing olfactory sensory input affects the rate of proliferation and the survival of postmitotic cells in the LC and in the HBC compared with control animals. The effect on the survival of postmitotic cells tested by BrdU injection followed by unilateral ablation is lateralized. Proliferation of neuronal precursor cells tested by the reversed experimental order was drastically impaired bilaterally. We conclude that the olfactory sensory input is necessary for a normal rate of proliferation of neuronal precursors and the survival of their progeny in the LC and in the HBC of C. maenas.
STUDY DESIGN: A basic science animal investigation. OBJECTIVES: To determine if bipedal rats differ in upright posture compared with quadrupedal rats. SUMMARY OF BACKGROUND DATA: It has been reported that surgically induced bipedalism in the rat leads to habitual upright posture. Based on this finding, bipedal rats have been used to study the changes erect posture induces in bone, ligament, muscle, and intervertebral discs. Previous studies have used direct observation as a means to describe posture. This study is the first to quantify postural differences between bipedal and quadrupedal rats. METHODS: Eleven bipedal rats were created by forelimb and tail amputation within 24 hours of birth. Eleven quadrupedal rats served as controls. Specialized cages were used with infrared sensors, and a computer program measured the total amount of time in the upright stance, the number of stands, and the amount of horizontal movement in the upright stance. Statistical comparisons were made between bipedal and quadrupedal rats hourly and over a 24-hour period of time. RESULTS: Quadrupedal rats assumed an upright posture for a significantly greater amount of time than bipedal rats when monitored over 24 hours (P = 0.016). Quadrupedal and bipedal rats did not differ in the number of stands (P = 0.63) or in the amount of horizontal movement in the upright stance (P = 0.34) over 24 hours. Similar results were obtained when comparing hourly intervals. CONCLUSION: This study quantifiably indicates that bipedal rats do not assume a more erect posture and spend no more time in an upright position compared with quadrupedal rats. The upright posture may not be the cause of some previously reported anatomic changes observed in the bipedal rat.
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