The enrichment of knowledge about the microstructure of brown bear compact bone tissue

Figures & data

Figure 1. Microstructure of femoral bone in brown bears cubs. 1: non-vascular bone tissue, 2: dense Haversian bone tissue, 3: plexiform bone tissue with isolated secondary osteons, orange arrows: lines of arrested growth (LAGs).

Figure 2. Microstructure of femoral bone in adult brown bears. 1: non-vascular bone tissue, 2: dense Haversian bone tissue, 3: plexiform bone tissue with isolated secondary osteons, orange arrows: lines of arrested growth (LAGs).

Table I. Schematic histomorphological data on the bear compact bone tissue

	adult			cub
type of bone tissue	zone			zone
	subperiosteal	mesosteal	subendosteal	subperiosteal	mesosteal	subendosteal
non vascular	+++	-	+++	++++	-	++++
plexiform	++	+	++	+++	+++	+++
irregular Haversian	+	++	+	-	++	-
dense Haversian	-	++++	-	-	+	-

The data come from several independent researchers and are shown on the basis of the percentage amount of three different type of bone tissue, as follow: -, absent; +, low presence (1–20%); ++, low-medium presence (21–50%); +++, high-medium presence (51–80%); ++++, high presence (81–100%). No differences have been noted between males and females.

Table II. Morphometrical results of brown bears compact bone tissue

structures	bear	n	area (µm^2)	perimeter (µm)	max. diameter (µm)	min. diameter (µm)
Haversian canals	8–9 m cub male	291	855.21 ± 441.22	104.36 ± 21.92	36.10 ± 7.87	30.20 ± 6.52
	18 m cub male	103	792.14 ± 158.41	99.43 ± 9.76	33.31 ± 3.24	30.29 ± 3.43
	24 m cub male	112	728.83 ± 161.50	95.52 ± 10.53	32.35 ± 3.71	28.70 ± 3.47
	6 years old male	439	819.16 ± 286.09	101.67 ± 14.95	34.01 ± 4.99	30.69 ± 4.92
	7 years old male	356	833.80 ± 220.65	102.50 ± 13.09	34.29 ± 4.31	30.95 ± 4.51
	6 years old female	372	802.89 ± 353.17	101.12 ± 18.44	33.60 ± 6.10	30.44 ± 5.95
	11 years old female	305	793.76 ± 196.69	100.24 ± 11.68	33.34 ± 3.91	29.80 ± 4.03
secondary osteons	8–9 m cub male	291	12,129.77 ± 3,053.08	391.86 ± 48.78	131.58 ± 17.21	117.43 ± 15.41
	18 m cub male	103	13,033.02 ± 3,161.28	405.11 ± 46.90	133.32 ± 15.88	124.54 ± 15.29
	24 m cub male	112	13,347.03 ± 2,925.09	410.16 ± 44.75	135.85 ± 15.23	125.16 ± 14.46
	6 years old male	439	12,180.69 ± 3,301.56	391.14 ± 51.61	130.11 ± 17.46	119.26 ± 16.58
	7 years old male	356	13,380.13 ± 3,204.16	404.53 ± 49.87	134.84 ± 14.92	122.58 ± 13.04
	6 years old female	372	13,057 ± 2,644.81	412.80 ± 42.36	136.39 ± 18.13	126.53 ± 18.55
	11 years old female	305	12,320.62 ± 3,362.97	389,47 ± 40.85	129.36 ± 17.57	118.64 ± 17.00

Legend: values represent means ± standard deviations; n - number of measurements; (*) p < 0.05.

Figure 3. Scatter plots showing the correlation between mean osteon diameter and mean Haversian canal diameter both in cubs and adult bears. Values are expressed in μm.

Table III. Data of the eccentricity (e) of osteons and Haversian canals in brown bears

	n	Osteon eccentricity ± SD	Haversian canal eccentricity ± SD	percentage of differential eccentricity in osteons compared to Haversian canals
8-9 m cub male	291	0.451 ± 0.02	0.548 ± 0.07	− 17.9%
18 m cub male	103	0.357 ± 0.03	0.416 ± 0.04	− 14.2%
24 m cub male	112	0.389 ± 0.02	0.461 ± 0.05	− 15.6%
6 years old male	439	0.400 ± 0.03	0.431 ± 0.05	− 7.2%
7 years old male	356	0.417 ± 0.05	0.430 ± 0.04	− 3.2%
6 years old female	372	0.373 ± 0.04	0.423 ± 0.03	− 11.8%
11 years old female	305	0.399 ± 0.03	0.448 ± 0.03	− 10.1%

Legend: SD - standard deviations; n - number of osteons measured.

Table IV. Statistical data on the variance of osteon diameter, Pearson’s correlation, and regression-line functions of the correlation between the diameter of osteons and Haversian canals

			Haversian canal diameter (HC.Dm)
		variance	Pearson’s coefficient	function of regression line	correlation
Osteon diameter (On.Dm)	8–9 m cub male	266.87	r = 0.266	On.Dm = 0,8259HC.Dm + 97,128	*
	18 m cub male	242.96	r = 0.252	On.Dm = 1,2039HC.Dm + 90,647	*
	24 m cub male	205.68	r = 0.223	On.Dm = 0,927HC.Dm + 102,2	*
	all cub bears	238.50	r = 0.268	On.Dm = 0,7622HC.Dm + 102,55	*
	6 years old male	289.84	r = 0.315	On.Dm = 0,605HC.Dm + 105,11	**
	7 years old male	251.57	r = 0.426	On.Dm = 1,733HC.Dm + 72,647	**
	6 years old female	347.19	r = 0.517	On.Dm = 1,521HC.Dm + 82,763	***
	11 years old female	297.99	r = 0.341	On.Dm = 1,496HC.Dm + 76,31	**
	all adult bears	295.28	r = 0.394	On.Dm = 0,8021HC.Dm + 99,48	**
	all bears	271.35	r = 0.284	On.Dm = 0,7785HC.Dm + 101,17	**

Data refer to mean diameter. Correlation: *** moderate positive; ** low positive; * little correlation.