Texas A&M University Veterinary Medicine
& Biomedical Sciences
Texas A&M University
Texas A&M University Veterinary Medicine
& Biomedical Sciences
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Larry Johnson

Professor Emeritus Department of Veterinary Integrative Biosciences
Contact
LJOHNSON@cvm.tamu.edu
9798459279
TAMU Mailstop: 4458

Research and Scholarly Interests

toxicology; histology; spermatogenesis; gamete physiology; gene expression of Sertoli cells; aging of the testis; seasonal reproductive changes; infertility in males and promotion of science in youth.

EDUCATION

  • B.S., North Carolina State University, 1971
  • M.S., Virginia PI and State University, 1974
  • Ph.D., Colorado State University, 1978
  • Post Doc, University of Texas Health Science Center, 1980
  • Reproductive Biology
  • Anatomy
  • Physiology
  • Education
  • Brinsko SP, Varner DD, Blanchard TL, Relford RL, Johnson L (1992). Bilateral infectious epididymitis in a stallion. EQUINE VET J. 4, 325-8
  • Johnson L, Varner DD, Tatum ME, Scrutchfield WL (1991). Season but not age affects Sertoli cell number in adult stallions. BIOL REPROD. 3, 404-10
  • Johnson L, Thompson DL Jr, Varner DD (2008). Role of Sertoli cell number and function on regulation of spermatogenesis. ANIM REPROD SCI. 1-2, 23-51
  • Johnson L, Blanchard TL, Varner DD, Scrutchfield WL (1997). Factors affecting spermatogenesis in the stallion. THERIOGENOLOGY. 7, 1199-216
  • Lee B, Pine M, Johnson L, Rettori V, Hiney JK, Dees WL (2006). Manganese acts centrally to activate reproductive hormone secretion and pubertal development in male rats. REPROD TOXICOL. 4, 580-5
  • Johnson L, Staub C, Silge RL, Harris MW, Chapin RE (2002). The pesticide methoxychlor given orally during the perinatal/juvenile period, reduced the spermatogenic potential of males as adults by reducing their Sertoli cell number. REPROD NUTR DEV. 6, 573-80
  • Staub C, Hardy VB, Chapin RE, Harris MW, Johnson L (2002). The hidden effect of estrogenic/antiandrogenic methoxychlor on spermatogenesis. TOXICOL APPL PHARMACOL. 2, 129-35
  • Johnson L, Staub C, Neaves WB, Yanagimachi R (2001). Live human germ cells in the context of their spermatogenic stages. HUM REPROD. 8, 1575-82
  • Johnson L, Varner DD, Roberts ME, Smith TL, Keillor GE, Scrutchfield WL (2000). Efficiency of spermatogenesis: a comparative approach. ANIM REPROD SCI. 60-61, 471-80
  • Varner DD, Scanlan CM, Thompson JA, Brumbaugh GW, Blanchard TL, Carlton CM, Johnson L (1998). Bacteriology of preserved stallion semen and antibiotics in semen extenders. THERIOGENOLOGY. 4, 559-73
  • Blanchard T, Varner D, Johnson L, Roser J, Hill J, Miller C (2000). Testicular and hormonal changes in stallions with thermally induced testicular degeneration. J REPROD FERTIL SUPPL. 56, 51-9
  • Johnson L, Neaves WB, Barnard JJ, Keillor GE, Brown SW, Yanagimachi R (1999). A comparative morphological study of human germ cells in vitro or in situ within seminiferous tubules. BIOL REPROD. 4, 927-34
  • Cerelli JS, Johnson L (1999). Potential daily sperm production, Sertoli cell number, and seminiferous tubule characteristics in beef bulls fed conventional or gossypol-enriched diets. J ANDROL. 4, 519-28
  • Johnson L, Barnard JJ, Rodriguez L, Smith EC, Swerdloff RS, Wang XH, Wang C (1998). Ethnic differences in testicular structure and spermatogenic potential may predispose testes of Asian men to a heightened sensitivity to steroidal contraceptives. J ANDROL. 3, 348-57
  • Blanchard TL, Johnson L (1997). Increased germ cell degeneration and reduced germ cell:Sertoli cell ratio in stallions with low sperm production. THERIOGENOLOGY. 3, 665-77
  • Blanchard TL, Johnson L (1997). Determination of daily sperm production in stallion testes by enumeration of germ cells in homogenates. THERIOGENOLOGY. 3, 655-64
  • Wilker C, Johnson L, Safe S (1996). Effects of developmental exposure to indole-3-carbinol or 2,3,7,8-tetrachlorodibenzo-p-dioxin on reproductive potential of male rat offspring. TOXICOL APPL PHARMACOL. 1, 68-75
  • Johnson L, Suggs LC, Norton YM, Welsh TH Jr, Wilker CE (1996). Effect of hypophysectomy, sex of host, and/or number of transplanted testes on Sertoli cell number and testicular size of syngeneic testicular grafts in Fischer rats. BIOL REPROD. 5, 960-9
  • Okwun OE, Igboeli G, Ford JJ, Lunstra DD, Johnson L (1996). Number and function of Sertoli cells, number and yield of spermatogonia, and daily sperm production in three breeds of boar. J REPROD FERTIL. 1, 137-49
  • Johnson L, Mckenzie KS, Snell JR (1996). Partial wave in human seminiferous tubules appears to be a random occurrence. TISSUE CELL. 2, 127-36
  • Johnson L (1995). Efficiency of spermatogenesis. MICROSC RES TECH. 5, 385-422
  • Clemmons AJ, Thompson DL Jr, Johnson L (1995). Local initiation of spermatogenesis in the horse. BIOL REPROD. 6, 1258-67
  • Wilker CE, Welsh TH Jr, Safe SH, Narasimhan TR, Johnson L (1995). Human chorionic gonadotropin protects Leydig cell function against 2,3,7,8-tetrachlorodibenzo-p-dioxin in adult rats: role of Leydig cell cytoplasmic volume. TOXICOLOGY. 1-3, 93-102
  • Johnson L (1994). A new approach to study the architectural arrangement of spermatogenic stages revealed little evidence of a partial wave along the length of human seminiferous tubules. J ANDROL. 5, 435-41
  • Johnson L, Wilker CE, Safe SH, Scott B, Dean DD, White PH (1994). 2,3,7,8-Tetrachlorodibenzo-p-dioxin reduces the number, size, and organelle content of Leydig cells in adult rat testes. TOXICOLOGY. 1, 49-65
  • Johnson L, Carter GK, Varner DD, Taylor TS, Blanchard TL, Rembert MS (1994). The relationship of daily sperm production with number of Sertoli cells and testicular size in adult horses: role of primitive spermatogonia. J REPROD FERTIL. 1, 315-21
  • Varner DD, Bowen JA, Johnson L (1993). Effect of heparin on capacitation/acrosome reaction of equine sperm. ARCH ANDROL. 3, 199-207
  • Chaturvedi PK, Johnson L (1993). Architectural arrangement of stages of the spermatogenic cycle within human seminiferous tubules is related to efficiency of spermatogenesis. CELL TISSUE RES. 1, 65-70
  • Johnson L, Dickerson R, Safe SH, Nyberg CL, Lewis RP, Welsh TH Jr (1992). Reduced Leydig cell volume and function in adult rats exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin without a significant effect on spermatogenesis. TOXICOLOGY. 2, 103-18
  • Johnson L, Chaturvedi PK, Williams JD (1992). Missing generations of spermatocytes and spermatids in seminiferous epithelium contribute to low efficiency of spermatogenesis in humans. BIOL REPROD. 6, 1091-8
  • Johnson L, Bartke A (1991). Effect of photoperiod on the rate of 3H-thymidine incorporation of epididymal principal cells in adult Syrian hamsters. J EXP ZOOL. 1, 89-94
  • Varner DD, Vaughan SD, Johnson L (1991). Use of a computerized system for evaluation of equine spermatozoal motility. AM J VET RES. 2, 224-30
  • Johnson L (1991). Seasonal differences in equine spermatocytogenesis. BIOL REPROD. 2, 284-91
  • Johnson L, Varner DD, Thompson DL Jr (1991). Effect of age and season on the establishment of spermatogenesis in the horse. J REPROD FERTIL SUPPL. 44, 87-97
  • Johnson L, Kattan-Said AF, Hardy VB, Scrutchfield WL (1990). Isolation and staging of horse seminiferous tubules by transillumination. J REPROD FERTIL. 2, 689-96
  • Johnson L, Hardy VB, Martin MT (1990). Staging equine seminiferous tubules by Nomarski optics in unstained histologic sections and in tubules mounted in toto to reveal the spermatogenic wave. ANAT REC. 2, 167-74
  • Johnson L, Grumbles JS, Chastain S, Goss HF Jr, Petty CS (1990). Leydig cell cytoplasmic content is related to daily sperm production in men. J ANDROL. 2, 155-60
  • Johnson L, Grumbles JS, Bagheri A, Petty CS (1990). Increased germ cell degeneration during postprophase of meiosis is related to increased serum follicle-stimulating hormone concentrations and reduced daily sperm production in aged men. BIOL REPROD. 2, 281-7
  • Blanchard TL, Varner DD, Brinsko SP, Meyers SA, Johnson L (1989). Effects of postparturient uterine lavage on uterine involution in the mare. THERIOGENOLOGY. 4, 527-35
  • Johnson L, Tatum ME (1989). Temporal appearance of seasonal changes in numbers of Sertoli cells, Leydig cells, and germ cells in stallions. BIOL REPROD. 5, 994-9
  • Johnson L (1989). Evaluation of the human testis and its age-related dysfunction. PROG CLIN BIOL RES. 302, 35-60
  • Johnson L, Varner DD (1988). Effect of daily spermatozoan production but not age on transit time of spermatozoa through the human epididymis. BIOL REPROD. 4, 812-7
  • Johnson L, Abdo JG, Petty CS, Neaves WB (1988). Effect of age on the composition of seminiferous tubular boundary tissue and on the volume of each component in humans. FERTIL STERIL. 6, 1045-51
  • Johnson L, Matt KS, Bartke A, Nguyen HB, Le HT (1987). Effect of photoperiod on the size of the Leydig cell population and the rate of recruitment of Leydig cells in adult Syrian hamsters. BIOL REPROD. 3, 727-38
  • Larry Johnson, Nancy H. Ing, Kevin O. Curley Jr., Christophe Staub, Jennifer Graham, and Thomas H. Welsh, Jr. (2014). Anatomy and physiology of the male reproductive system and potential targets of toxicants.

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